A frequency modulation (hereinafter referred to as “FM”) demodulation receiver is easily affected by threshold effect. When the amplitude of noise is larger than the amplitude of a signal, threshold effect happens so that received signal phase is affected, multiple spikes are observed on demodulated signal, and signal to noise ratio (SNR) rapidly deteriorates. If installing a phase lock loop (PLL) in an FM demodulation receiver, the onset of threshold effect may be pushed to lower signal level, which results in better receiver performance; however, some shortages could be unavoidable. The phase lock loop installed in an FM demodulation receiver usually operates with a voltage controlled oscillator. Since a phase lock loop and a voltage controlled oscillator are both high-priced components, the related hardware cost is difficult to be reduced. Power consumption of the circuit configuration of the prior art is high for using these components. Hence, an FM demodulation receiver of lower cost, smaller power consumption and better ability against threshold effect is required in the related field.